logging in or signing up collision theory AlNiedz Download Post to : URL : Related Presentations : Share Add to Flag Embed Email Send to Blogs and Networks Add to Channel Uploaded from authorPOINTLite Insert YouTube videos in PowerPont slides with aS Desktop Copy embed code: (To copy code, click on the text box) Embed: URL: Thumbnail: WordPress Embed Customize Embed The presentation is successfully added In Your Favorites. Views: 1018 Category: Science & Tech.. License: All Rights Reserved Like it (0) Dislike it (0) Added: February 01, 2010 This Presentation is Public Favorites: 0 Presentation Description No description available. Comments Posting comment... Premium member Presentation Transcript Reaction Rates Prepared by Barbara Andreswith A. NiedzvieckiApril 5, 2004@ Centennial Regional High School : Reaction Rates Prepared by Barbara Andreswith A. NiedzvieckiApril 5, 2004@ Centennial Regional High School Factors which influence reaction rates: : Factors which influence reaction rates: Temperature Presence of a catalyst Concentration of reactants Surface area of reactants Type of reactants How can we explain these factors? : How can we explain these factors? Collision Theory : Collision Theory Reaction rate depends on: : Reaction rate depends on: # of collision per unit time Success rate Success depends on the: : Success depends on the: Collision geometry (orientation) Energy of the collision Collision Geometry : Collision Geometry H2(g) + I2(g) 2HI(g) Side-to-Side Collision : H2(g) + I2(g) 2HI(g) Side-to-Side Collision Slide 9: H2(g) + I2(g) X 2HI(g) End-to-End Collision Slide 10: H2(g) + I2(g) X 2HI(g) Glancing Collision HCl(g) + C2H4(g) products : HCl(g) + C2H4(g) products For this example: Hydrogen end of H-Cl approaches C=C double bond ….. Success All other collisions …..“rebound” Which of the following collisions will be successful? : Which of the following collisions will be successful? X X X Energy of the Collision : Energy of the Collision Slide 14: Particles (molecules & atoms) must collide with a minimum energy Minimum energy called the activation energy of the reaction Remember, the energy profile for an exothermic reaction looks like this: : Remember, the energy profile for an exothermic reaction looks like this: In order for a reaction to occur the: : In order for a reaction to occur the: activation energy “barrier” must be overcome collision energy activation energy bond breaking & bond formation (reaction) collision energy < activation energy “rebound” (no reaction) For any reacting system: : For any reacting system: Particles have a very wide range of energies What proportion of the particles have high enough energies to react when they collide? Slide 18: Maxwell-Boltzmann Distribution (gases) Area under the curve = total number of particles present Slide 19: Maxwell-Boltzmann Distribution (gases) To enable low energy particles to react we have to: : To enable low energy particles to react we have to: change the shape of the curve or move the activation energy to the left How can we change the shape of the curve? : How can we change the shape of the curve? Change the temperature of the reaction Slide 22: How can we overcome the activation energy “barrier”? Slide 23: Effect of Temperature on Reaction Rates Temperature Reaction Rate : Temperature Reaction Rate For many reactions happening at around room temperature, the rate of reaction doubles for every 10°C rise in temperature. Why does this occur? : Why does this occur? Increased collision frequency Particles only react when they collide. Heat a substance … the particles move faster Collide more frequently Increased rate of reaction Slide 26: Increased kinetic energy Overcome activation energy “barrier” Heat a substance … the particles move faster Collisions are more “intense” Increased rate of reaction. Temperature … graph shape altered : Temperature … graph shape altered Area under a curve = count of # of particles “T + t” area doubled Doubled rate of reaction Slide 28: Effect of a Catalyst on Reaction Rates Catalysts are substances that: : Catalysts are substances that: speed up a reaction participate in the reaction steps are chemically unchanged at the end of the reaction have no loss of mass after the reaction Catalysts … : Catalysts … provide an alternative way for the reaction to happen which has a lower activation energy move the activation energy to the left on Maxwell-Boltzmann Distribution graph. Maxwell-Boltzmann Distribution : Maxwell-Boltzmann Distribution On an energy profile: : On an energy profile: Slide 33: Effect of Concentration on Reaction Rates Slide 34: Na2S2O3(aq) + 2 HCl S(s) + SO2(aq) + 2 NaCl(aq) + H2O(l) Dilute HCl is added to sodium thiosulphate solution …. precipitate of sulphur forms Sodium thiosulphate solution diluted …. precipitate takes longer and longer to form. Case 1: Reactions - 2 Particles : Case 1: Reactions - 2 Particles Must first collide Concentration is higher the chance of collision are greater. Slide 36: Case 2: Catalyst already working as fast as it can Small amount of a solid catalyst in a reaction High concentration of reactants Catalyst completely “occupied” Adding more reactants has no effect Slide 37: Case 3: Certain Multi-step Reactions Slide 38: Pressure Concentration Reaction Rate Mass of gas … squeezed into a smaller volume Relationship Between Pressure and Concentration Can also be explained by the ideal gas law … : Can also be explained by the ideal gas law … Slide 40: Effect of Surface Area on Reaction Rates Surface Area Reaction Rate : Surface Area Reaction Rate Particles in the gas or liquid must collide with the solid particles Increasing the surface area of the solid increases the chances of collision taking place Slide 42: 2Mg(s)+ 2 HCl(aq) H2(g)+2 MgCl Slide 43: Effect of Nature of Reactants on Reaction Rates We have studied the following two reactions: : We have studied the following two reactions: C25H52(s) + 38 O2(g) 25 CO2(g) + 26 H2O(g) 2 CH3OH(l) + 3 O2(g) 2 CO2(g) + 4 H2O(g) Based on experimental results, how did the nature of reactants affects the rate of reaction: # of bond broken and formed reaction rate We have studied the following two reactions: : We have studied the following two reactions: C25H52(s) + 38 O2(g) 25 CO2(g) + 26 H2O(g) 2 CH3OH(l) + 3 O2(g) 2 CO2(g) + 4 H2O(g) Explain this based on Collision Theory We have studied the following two reactions: : We have studied the following two reactions: C25H52(s) + 38 O2(g) 25 CO2(g) + 26 H2O(g) 2 CH3OH(l) + 3 O2(g) 2 CO2(g) + 4 H2O(g) Explain this based on Collision Theory Greater # of collisions required The End : The End You do not have the permission to view this presentation. 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collision theory AlNiedz Download Post to : URL : Related Presentations : Share Add to Flag Embed Email Send to Blogs and Networks Add to Channel Uploaded from authorPOINTLite Insert YouTube videos in PowerPont slides with aS Desktop Copy embed code: (To copy code, click on the text box) Embed: URL: Thumbnail: WordPress Embed Customize Embed The presentation is successfully added In Your Favorites. Views: 1018 Category: Science & Tech.. License: All Rights Reserved Like it (0) Dislike it (0) Added: February 01, 2010 This Presentation is Public Favorites: 0 Presentation Description No description available. Comments Posting comment... Premium member Presentation Transcript Reaction Rates Prepared by Barbara Andreswith A. NiedzvieckiApril 5, 2004@ Centennial Regional High School : Reaction Rates Prepared by Barbara Andreswith A. NiedzvieckiApril 5, 2004@ Centennial Regional High School Factors which influence reaction rates: : Factors which influence reaction rates: Temperature Presence of a catalyst Concentration of reactants Surface area of reactants Type of reactants How can we explain these factors? : How can we explain these factors? Collision Theory : Collision Theory Reaction rate depends on: : Reaction rate depends on: # of collision per unit time Success rate Success depends on the: : Success depends on the: Collision geometry (orientation) Energy of the collision Collision Geometry : Collision Geometry H2(g) + I2(g) 2HI(g) Side-to-Side Collision : H2(g) + I2(g) 2HI(g) Side-to-Side Collision Slide 9: H2(g) + I2(g) X 2HI(g) End-to-End Collision Slide 10: H2(g) + I2(g) X 2HI(g) Glancing Collision HCl(g) + C2H4(g) products : HCl(g) + C2H4(g) products For this example: Hydrogen end of H-Cl approaches C=C double bond ….. Success All other collisions …..“rebound” Which of the following collisions will be successful? : Which of the following collisions will be successful? X X X Energy of the Collision : Energy of the Collision Slide 14: Particles (molecules & atoms) must collide with a minimum energy Minimum energy called the activation energy of the reaction Remember, the energy profile for an exothermic reaction looks like this: : Remember, the energy profile for an exothermic reaction looks like this: In order for a reaction to occur the: : In order for a reaction to occur the: activation energy “barrier” must be overcome collision energy activation energy bond breaking & bond formation (reaction) collision energy < activation energy “rebound” (no reaction) For any reacting system: : For any reacting system: Particles have a very wide range of energies What proportion of the particles have high enough energies to react when they collide? Slide 18: Maxwell-Boltzmann Distribution (gases) Area under the curve = total number of particles present Slide 19: Maxwell-Boltzmann Distribution (gases) To enable low energy particles to react we have to: : To enable low energy particles to react we have to: change the shape of the curve or move the activation energy to the left How can we change the shape of the curve? : How can we change the shape of the curve? Change the temperature of the reaction Slide 22: How can we overcome the activation energy “barrier”? Slide 23: Effect of Temperature on Reaction Rates Temperature Reaction Rate : Temperature Reaction Rate For many reactions happening at around room temperature, the rate of reaction doubles for every 10°C rise in temperature. Why does this occur? : Why does this occur? Increased collision frequency Particles only react when they collide. Heat a substance … the particles move faster Collide more frequently Increased rate of reaction Slide 26: Increased kinetic energy Overcome activation energy “barrier” Heat a substance … the particles move faster Collisions are more “intense” Increased rate of reaction. Temperature … graph shape altered : Temperature … graph shape altered Area under a curve = count of # of particles “T + t” area doubled Doubled rate of reaction Slide 28: Effect of a Catalyst on Reaction Rates Catalysts are substances that: : Catalysts are substances that: speed up a reaction participate in the reaction steps are chemically unchanged at the end of the reaction have no loss of mass after the reaction Catalysts … : Catalysts … provide an alternative way for the reaction to happen which has a lower activation energy move the activation energy to the left on Maxwell-Boltzmann Distribution graph. Maxwell-Boltzmann Distribution : Maxwell-Boltzmann Distribution On an energy profile: : On an energy profile: Slide 33: Effect of Concentration on Reaction Rates Slide 34: Na2S2O3(aq) + 2 HCl S(s) + SO2(aq) + 2 NaCl(aq) + H2O(l) Dilute HCl is added to sodium thiosulphate solution …. precipitate of sulphur forms Sodium thiosulphate solution diluted …. precipitate takes longer and longer to form. Case 1: Reactions - 2 Particles : Case 1: Reactions - 2 Particles Must first collide Concentration is higher the chance of collision are greater. Slide 36: Case 2: Catalyst already working as fast as it can Small amount of a solid catalyst in a reaction High concentration of reactants Catalyst completely “occupied” Adding more reactants has no effect Slide 37: Case 3: Certain Multi-step Reactions Slide 38: Pressure Concentration Reaction Rate Mass of gas … squeezed into a smaller volume Relationship Between Pressure and Concentration Can also be explained by the ideal gas law … : Can also be explained by the ideal gas law … Slide 40: Effect of Surface Area on Reaction Rates Surface Area Reaction Rate : Surface Area Reaction Rate Particles in the gas or liquid must collide with the solid particles Increasing the surface area of the solid increases the chances of collision taking place Slide 42: 2Mg(s)+ 2 HCl(aq) H2(g)+2 MgCl Slide 43: Effect of Nature of Reactants on Reaction Rates We have studied the following two reactions: : We have studied the following two reactions: C25H52(s) + 38 O2(g) 25 CO2(g) + 26 H2O(g) 2 CH3OH(l) + 3 O2(g) 2 CO2(g) + 4 H2O(g) Based on experimental results, how did the nature of reactants affects the rate of reaction: # of bond broken and formed reaction rate We have studied the following two reactions: : We have studied the following two reactions: C25H52(s) + 38 O2(g) 25 CO2(g) + 26 H2O(g) 2 CH3OH(l) + 3 O2(g) 2 CO2(g) + 4 H2O(g) Explain this based on Collision Theory We have studied the following two reactions: : We have studied the following two reactions: C25H52(s) + 38 O2(g) 25 CO2(g) + 26 H2O(g) 2 CH3OH(l) + 3 O2(g) 2 CO2(g) + 4 H2O(g) Explain this based on Collision Theory Greater # of collisions required The End : The End